1. Field of the Invention
The present invention relates to an apparatus and method for insulating beverage containers and container stock material. In particular, the present invention relates to an insulated, paper-based beverage container or stock material having improved insulation properties and a method of producing these insulated containers or stock materials.
2. Description of the Background Art
Current standard paper cup stock permits excessive heat transfer through the wall of an insulated beverage container. Accordingly, a user""s hand becomes uncomfortably or sometimes even painfully hot when excessive heat transfer is permitted through the container wall. This may require the user to be inconvenienced by having to release the container due to the excessive heat of the container""s contents. An analogous but opposite situation can occur with very cold beverages, where heat transfer from a user""s hand is transferred rapidly to the contents of the container.
U.S. Pat. No. 4,435,344 to Ioka describes a method for producing an insulating composite paper container having a body member and a bottom member. The body member is formed of paper coated or laminated with a thermoplastic synthetic resin film. A surface of the body member is then heated to form a foamed polyethylene heat-insulating layer on either or both of inner and outer surfaces of the container""s body member. The heat-insulated body member is then attached to the bottom member.
U.S. Pat. Nos. 6,030,476 and 5,840,139 to Geddes et al. describe a method for producing insulating beverage containers or cups, stock material and containers made therefrom. A stock material includes a base layer, an insulating layer formed on a portion of the base layer, and a printed pattern/mineral oil applied to the insulating layer. The insulating layer is formed from a thermoplastic synthetic resin film. U.S. Pat. No. 6,030,476 describes a polyethylene foam taught on the outside surface of the paper cup.
European Patent Application EP 0940240 A2 describes a heat insulating paper cup with targeted insulation in areas where printed matter exists. The body member of the cup is coated on its outside surface with a foamable synthetic resin and on its inside surface with an inside surface laminate of a synthetic resin effective to prevent liquid penetration. The bottom panel member is optionally coated on its upper surface with a foamed or an unfoamed synthetic resin. Printed matter is provided prior to foaming of the synthetic resin on the outer surface of the cup with water-based ink. Further, the low density polyethylene is foamed by vaporizing the water contained in the paper stock.
European Patent Application EP 1060879 A2 describes a heat insulating paper cup having a body member partially or fully coated on its outside surface with a foamed low density polyethylene and coated on its inside surface with an unfoamed modified low density polyethyelene.
However, the devices and methods of the background art suffer from the following disadvantages. Other known designs sacrifice the outside printability of the cup to provide insulation or do not provide adequate insulation properties. As described above, many designs necessitate application of printed material prior to the manufacture of the paper cup, thereby limiting the ability to print or graphically enhance the cups after they have been manufactured.
The related art has not yet achieved insulated paper stock that is capable of effectively impeding heat transfer between the contents of the container and the exterior. In addition, adequate thermal insulation is not achieved from the related art in a manner that is cost effective.
The present invention overcomes the shortcomings associated with conventional devices and methods, and achieves other advantages not realized by conventional devices and methods.
It is an aspect of the present invention to provide an insulated beverage container, sleeve or stock material that reduces the energy transfer through a container wall, offers increased functionality and usefulness.
It is an aspect of the present invention to provide a container, sleeve, or stock material having superior hold times and pre-disposed to high quality printing and graphics.
The present invention is a recognition, in part, that the ability to produce blank paper cups, sleeves or stock material that can be printed/graphically enhanced is desirable. This invention permits a superior insulating cup product to be made from standardized manufacturing processes.
These and other aspects of the present invention are accomplished by an insulated beverage container stock material comprising a paper stock layer and a foam layer disposed along an interior surface of the paper stock layer. The foam layer can be adhered directly or indirectly to the paper stock layer by melt extrusion, lamination or foam extrusion.
These and other aspects of the present invention are further accomplished by an insulated beverage container comprising a container wall having a side portion; a bottom portion engaging said container wall along a lower side portion; a paper stock layer arranged along an exterior surface of said container wall; a thin polyethylene film layer; and a foam layer arranged along an interior surface of the container wall, the foam layer sandwiched between the polyethylene film layer and the paper stock layer. Optionally, the thin polyethylene film layer can be sandwiched between the foam layer and the paper stock. Also, optionally two thin polyethylene film layers can be used, one on each side of the foam layer.
These and other aspects of the present invention are further accomplished by a method of producing an insulated beverage container, comprising the steps of providing a paper cupstock having a container wall for surrounding a beverage containing space, a bottom portion, and a paper stock layer arranged along an exterior surface of said container wall; foaming a polymer into a foam layer by mixing a blowing agent into the polymer prior to foaming; and adhering the foam layer to the paper stock
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.